Recently, acceleration measuring devices, or accelerometers, are widely used for automobile airbags, suspension systems, position control systems of mobile bodies for the aeronautical or military use, and motion input devices and impact detection devices for electronic products such as computers or mobile phones.
Conventional accelerometers are classified into a servo type, a piezoelectric type, a piezoresistive type, and a capacitive type according to the types of operation. In these types of accelerometers, a mobile body having a mass “m” is accelerated at an acceleration “a” by applying a force “F” to the mobile body, in which F=ma. In this state, acceleration is obtained by measuring a control signal, a piezovoltage, a piezoresistance, or a capacitance which varies according to the displacement of the mobile body. To improve accuracy in measuring the acceleration in the above conventional accelerometers, a structure capable of accurately measuring the displacement of the mobile body that varies according to the acceleration is needed. However, such a mobile body requires a complicated manufacturing process and durability of accelerometers are deteriorated.
Meanwhile, the conventional convection type accelerator using the thermal convection of a fluid can be embodied as disclosed in U.S. Pat. Nos. 2,440,189, 2,455,394, 5,581,034, and 6,182,509 and Japanese Patent Nos. hei 7-260820 and 2000-193677. These convection type accelerometers exhibit sensitivity and response speed lower than accelerometers using the above mobile body. When the pressure of a fluid changes according to the change in the external pressure or temperature, acceleration cannot be accurately measured. Thus, a packaging method is limited and the external temperature needs to be measured separately.